It has long been known to house electrical fixtures such as switches and receptacles in an electrical outlet box. The outlet box permits the insertion of electrical wires into the box which are terminated to electrical fixtures. The fixtures then may be mounted to the box which provides protection to the fixtures as well as the wires terminated therein. The outlet box is then mounted to a wall at a convenient location to provide access. Most outlet boxes accommodate one or more electrical fixtures, which terminate standard 110 volt electrical wires.
Outlet boxes are available in a variety of configurations and sizes. The selection of which type of box to use is dependant upon the specifics of the application. The most commonly employed box is a single-gang outlet box, also referred to as a standard outlet box. The single-gang box is ideal for applications in which only one receptacle is required for the application. Standard outlet boxes have opening dimensions of approximately 3″×2¼″ and are available in a variety of depths. Double-gang and triple-gang boxes are also available, and they typically have the capacity to hold two and three receptacles respectively. A four inch (4″) square box is also commonly employed for multiple receptacle applications.
Typically, outlet boxes are mounted by affixing mounting ears to a wall stud or other structural member. In the usual application, the installer will offset the electrical box when installed on the wall studs in order to compensate for the thickness of any finishing material to be installed. The offset is intended to ensure the open face of the box is aligned flush with the finish material to conform to electrical codes. In addition, for some applications, such as exterior uses, there is a requirement to install electrical boxes on poured concrete walls, wherein the outlet box, may be mounted within a concrete structure. This is accomplished by attaching the box to a form in the desired location. The form is usually a wooden temporary structure used to contain the poured concrete in the desired shape that is removed after the concrete has hardened. The outlet box remains in the concrete after removal of the form.
However, in some applications the offset is insufficient to bring the open face of the box flush with the finish material. In these cases extensions must be installed by the electrician to bridge the gap between the box opening and the surface of the finish material. This can occur, for example, when ceramic or stone tile are added to the sheet rock wall material. the prior art methods for providing an extension after the finish materials are installed involve squeezing the extension between the box and the wall finishing material and using longer than normal screws to install the electrical device such as a switch or receptacle. Alternately, the box may provide additional pretapped holes for affixing an extension which the installer may use for attaching the extension before installing the electrical device. In either case additional time consuming labor is needed to adapt the box for use and compliance with electrical codes.
Therefore, it would be desirable to have an extension for an electrical box that can be easily installed to extend the open front perimeter of the box after the finishing materials are installed such that the perimeter will be flush with the finished wall surface to conform to electrical code requirements.